چكيده لاتين :
To determine NaCl effects on growth and some antioxidant enzymes activity, the internode cuttings of four potato cultivars (Solanum tuberosum L.), Agria, Kennebec (relatively salt tolerant), Diamant and Ajax (relatively salt sensitive) were grown on callus inducing media amended with 0, 50, 100 and 150 mM NaCl at dark conditions. Callus growth of all cultivars was significantly reduced under salt stress. Total superoxide dismutase (SOD) activity decreased in all cultivars when calli were grown in the presence of NaCl. Peroxidase (POD), H2O2 detoxifying enzyme activity increased under salt stress, but at higher NaCl levels the activity was reduced. On the other hand, SOD and POD isozyme profiles at 100 mM NaCl were different from that of the control. These differences were quantitative and were expressed more in terms of increased or decreased isozymes activities. In dark conditions, callus tissue underwent oxidative stress in the presence of NaCl. In these conditions, more than any other SOD isozymes, Mn-SOD seems to play a major role in the scavenging of superoxide radicals during NaCl stress. Therefore, the increased Mn-SOD activity in salt treated-calli could reflect sustained O2- production in the mitochondria. On the other hand, in spite of increased activities of Mn-SOD and POD, reactive oxygen species (ROS) had damaging effects on the plant cells due to the SOD reduced total activity. Generally, there was no difference between relatively salt sensitive and tolerant cultivars in response to NaCl stress.
